The invention relates to an image reading apparatus for optically forming a flat image such as a sheet or a three-dimensional image such as a liquid surface on a photoelectric conversion element, so that the photoelectric conversion element electrically reads such an image. More particularly, the present invention relates to an image reading apparatus for reading media such as bacteria or microorganisms for analysis.
Generally, an optical microscope has been used for observing a material cultivated on a medium such as liquid and a sheet to analyze a propagation state of bacteria or microorganisms. In recent years, a new inspection system has been available in which a photoelectric sensor such as CCD electrically reads such a medium and an image processing apparatus such as a computer analyzes data, and then the data is stored.
Conventionally, Japanese Patent Publication (Kokai) No. 09-121837 has disclosed a colony count measuring apparatus for reading a three-dimensional object. In the colony count measuring apparatus, a CCD camera is mounted on a stage such as a Petri dish for placing a specimen to be viewed. That is, a flat sensor is used for capturing an image. In this case, it is necessary to provide an enough distance between the specimen and the camera (between the stage and the camera) to obtain an entire image of the specimen. Also, it is necessary to use a light source with a high output for illuminating the entire specimen, thereby increasing a size of the apparatus.
Japanese Patent Publications (Kokai) No. 07-140561 and No. 09-179214 have disclosed other apparatus for reading a three-dimensional object. In the image forming apparatus, an optical system formed of a bar-shaped light source, a lens and a mirror is arranged above a stage for placing a specimen, and the optical system moves to sequentially read an image of the specimen in line. With this type of sequential reading method, it is possible to bend a light path with the mirror, and it is not necessary to use a light source with a high output, thereby making the apparatus smaller than the apparatus using the CCD camera disclosed in Japanese Patent Publication (Kokai) No. 09-121837.
In the image forming apparatus disclosed in Japanese Patent Publications (Kokai) No. 07-140561 and No. 09-179214, it is necessary to provide a space between the stage and the optical system for placing and adjusting the specimen at a predetermined reading position on the stage, thereby increasing a size of the apparatus. The apparatus is provided with a mechanism for mounting the optical system to be movable freely up and down so that a focus position can be freely changed. The mechanism moves the optical system (scanning unit) itself up and down, or moves a frame supporting the optical system up and down, so that the mechanism tends to be large, thereby increasing a size of the apparatus.
Japanese Patent Publication (Kokai) No. 06-189063 has disclosed a reading apparatus having a stage for placing an original to be viewed formed of a drawer mechanism moving between a reading position inside the apparatus and a setting position for placing the original on the stage outside the apparatus. In the reading apparatus, it is possible to adjust the object (original) to be viewed at the setting position outside the apparatus. Accordingly, it is possible to make the apparatus compact as compared with the image forming apparatus disclosed in Japanese Patent Publication (Kokai) No. 07-140561, in which it is necessary to provide a large space between the stage and the optical system at the reading position for the adjustment.
In the reading apparatus disclosed in Japanese Patent Publication (Kokai) No. 06-189063, the original is pressed against the reading unit so that an image surface of the original (specimen) is located at a focus position of the reading unit. Accordingly, it is difficult to handle a specimen in a liquid state or a gel state. Also, the reading apparatus is provided with a mechanism for rotating the stage to press the original against the reading unit, thereby increasing a size of the apparatus.
Japanese Patent No. 3410810 has disclosed a reading apparatus having a drawer mechanism for moving a stage between a reading position and a setting position, similar to the reading apparatus disclosed Japanese Patent Publication (Kokai) No. 06-189063. In the reading apparatus, the original is pressed against a reading unit so that an image surface of an original (specimen) is located at a focus position of the reading unit. Accordingly, it is difficult to handle a specimen in a liquid state or a gel state. The reading apparatus is also provided with a mechanism for moving the original up and down, thereby increasing a size and cost of the apparatus.
In view of the problems described above, an object of the present invention is to provide a compact image reading apparatus for reading a three-dimensional object such as liquid.
Another object of the present invention is to provide a compact and low-cost apparatus having a simple mechanism for adjusting a focus position.
Further objects and advantages of the invention will be apparent from the following description of the invention.